1. Field of the Invention
The present invention relates to household appliances, and more particularly to cooling systems such as those utilized in refrigerators, freezers and air conditioners.
2. Background Art
In the usual operation of appliances, such as refrigerators, freezers and air conditioners, the appliance includes a sensor inside each compartment and if it is a multi-compartment unit, such as a refrigerator with a freezer, a sensor in each compartment to cause the initiation of the operation of a compressor based on preestablished consumer user settings (cooler or warmer) establishing preset temperatures associated with the setting established by the user.
Normally, such preset temperatures are the same for each user setting, independent of ambient temperatures n which the appliances operated. As in the case of many refrigerators, some may include a single evaporator with different ways of transferring cold air to each compartment. Usually this involves some mechanical means, such as a sliding door or fan to let cold air move from one compartment to another compartment. Still other types may include a single evaporator with sections balanced between the two compartments. Frequently this balanced type utilizes a single sensor tot establishing the temperature regulation being satisfactory for both compartments only for a small range of external temperatures. Such single sensor units result in only one compartment with very good regulation for all external temperatures, while the temperature in the other has poor regulation with variance in external temperatures outside a very narrow range.
A search of the background art directed to the subject matter of the present invention and conducted in the U.S. Patent and Trademark Office disclosed the following U.S. Letters Patent:
U.S. Pat. No. 5,255,530 is drawn to a two-zone refrigerator temperature control, including an evaporator fan control led by the temperature within a fresh food compartment while the speed of the compressor motor and condenser fan are control led by a temperature sensor within the freezing compartment. PA1 U.S. Pat. No. 4,495,780 teaches a hermetically closed control box, or cabinet, with a plurality of calling devices included therein. One temperature sensor is included within the cabinet while another for detecting ambient temperatures is placed outside the control box. Comparator circuitry receives signals from the two sensors submitting them to logic control circuits to control cooling equipment. PA1 U.S. Pat. No. 5,187,941 is drawn to a refrigerator system that detects abnormally low temperature conditions in a particular portion of the fresh food compartment. If the sensed temperature fails to rise to a predetermined temperature within a particular range of time, an abnormal temperature condition is considered to exist requiring corrective action. PA1 U.S. Pat. No. 5,224,355 pertains to a plural temperature adjustment apparatus for a refrigerator whereby cooling is automatically changed based on temperature changes within the refrigerator itself. The system utilizes the input of data to a computer for refrigerator control. PA1 U.S. Pat. No. 4,718,247 is drawn to a system that teaches the driving of a refrigerator at a higher speed when the internal temperature of the freezer compartment or fresh food compartment rise temporarily. PA1 U.S. Pat. No. 4,916,912 pertains to defrosting of a heat pump wherein differences between exterior ambient temperatures and exterior heat exchanger temperatures are compared for determination of a difference function. Two sensors are utilized to determine operation of the system microprocessor.
The two sensors included deal with temperature interaction between the two compartments of the refrigerator.
Based on a thorough review of the above identified patents, we believe that none of the above teach, disclose or claim the novel combination of elements and functions found in the improved temperature control system taught by the present invention.
Accordingly, it is the object of the present invention to provide a temperature control system for a two compartment appliance utilizing a single sensor. A particular feature of the present invention is the utilization of information on the external ambient temperature to allow normal control of one compartment and indirect control of the second. The cooling system is arranged to operate differently for each user setting based on varying outside ambient temperatures. This method allows for a substantial improvement in temperature control accuracy for the compartment which does not contain a sensor.